Right before Facebook’s initial public offering this month, the company’s co-founder Eduardo Saverin has renounced his U.S. citizenship to live in Singapore. Many believe the reason for this move is to save money in federal taxes on the billions he will be receiving when Facebook goes public. However, his spokesperson assures the Los Angeles Times that Saverin wants to live in Singapore for an indefinite period of time in order to invest in companies that have “strong interests in entering the Asian markets.”

Others are not so happy with Saverin’s decision to ditch his U.S. citizenship. In fact, the Los Angeles Times reported that two U.S. senators have introduced legislation that would punish Americans for denouncing their citizenships in order to evade paying taxes.

Saverin was not always a U.S. citizen. He was born in Brazil in 1982, and became a U.S. citizen at age 16. He’s also not new to Singapore. Saverin has been living in the country for several years now. Singapore does not collect capital gains tax.

So how much will he be saving by renouncing his U.S. citizenship? According to financial news service Bloomberg, Saverin can save up to $67 million in federal taxes; he is expected to collect up to $3.84 billion.